# year    value 
 1980     0.05 
 1981     -0.1 
 1982     0.37 
 1983     0.27 
 1984     0.23 
 1985     0.15 
 1986     0.12 
 1987     0.61 
 1988     0.19 
 1989     0.04 
 1990      0.2 
 1991      0.3 
 1992     0.25 
 1993     0.26 
 1994     0.62 
 1995     0.56 
 1996     0.32 
 1997     1.17 
 1998     0.42 
 1999     0.04 
 2000     0.24 
 2001     0.38 
 2002     0.71 
 2003     0.86 
 2004     0.83 
 2005     0.46 
 2006     0.84 
 2007     0.52 
 2008     0.62 
 2009     1.02 
 2010     0.68 
 2011     0.57 
 2012     0.97 
 2013     0.75 
 2014     1.02 
 2015     1.26 
 2016     0.76 
 2017     0.81 
 2018     0.98